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 Overview of Update Cycle
 
 Process Overview
 
 The basic idea behind the update cycle is that the DataSource detects an update and then emits a signal telling all objects that
 are dependent on it to update and the loop continues until all updates are complete.
 
 Creation of connections
 
 The connections are all created by the dependent objects connecting to the source's signal.  Each object is responsible for
 knowing what objects it depends on and creating and disconnecting the links as necessary when changes are made to the object.
 
 Processing of updates
 
 Processing of updates is triggered by the UpdateManager each time the Timer for the minimum update cycle has triggered.  If a 
 change was detected the update cycle for the datasources that requested updates begins, otherwise it waits for another minimum
 update cycle.
 
 Detecting change
 
 Detecting the change to the datasource is the responsibility of the plugin.  There are two common ways to check.
 
 Timer
 
   Timer based detecting means that the plugin checks if the datasource has each each time the timer is triggered.
 
 File Based
 
   File or Data based detecting does not use a timer but is still constrained by the update cycle timer.  This uses
   QFileSystemWatcher to monitor the files on disk and when the file changes the update request is triggered.
 
 
 Requesing Update
 
 The update manager controls all updates, as such, if any object wants to update it must ask the UpdateManager.  When the 
 DataSource detects a change it tells the UpdateManager who, when the timer triggers, begins the update cycle by telling the
 DataSource it can notify it's dependents.
 
 Each Dependent then requests from the UpdateManager to update, and waits for permission to begin, this continues down the 
 line until all objects are updated.  The UpdateManager also requires each object indicate when it's update has started and 
 finished and uses this information to ensure that each type of update is completed before continuing to the next.  All
 DataVectors must be updated before any DataObjects and it continues for Relations and Plots until everything is updated
 in such a way as to prevent any data inconsistencies or reprocessing of data.
 
 
 Processing an Update
 
 Each object processes the update using it's update function and is entirely dependent on the object type.  In doing an update
 it must follow the following steps.
 
   0.  Get an update Signal from parent object.
   1.  Request Update from the UpdateManager
   2.  Wait for permission to begin.
   3.  Notify the UpdateManager it is starting.
   4.  Update the object.
   5.  emit the Update cycle for dependents to pick up.
   6.  Notify the UpdateManager it is finished.
 
 
 Debugging
 
 Debugging output is configured in updatemanager.h and provides two levels of debugging.
 
   1   UpdateManager based.  This outputs all data from the UpdateManager.  Lines denoted with UM -
   2   Full Debugging.  This also includes output from all Updatable objects as they are updating.  Lines denoted with UP -
 
 
 Sample Output from full debugging.
 
 UM - Allow updates triggered
 UM - Beginning update for "/home/kst2/kst/tests/dirfile_maker/dm.cur (DS-dm.cur)"
 # Beginning Update Cycle based on DataSource change.
         UM - Update beginning for "DS-dm.cur" for update "DS-dm.cur" update count 1
                 UP - Data Source update required by Vector "V1" for update of "DS-dm.cur"
 # DataSource has 3 Vectors configured for it.  Once update begins each Vector must be updated.
 # As each Vector begins updating the update count is incremented and when it finished is 
 # decremented.
                 UM - Update beginning for "V1" for update "DS-dm.cur" update count 2
                         UP - Vector "V1" has been updated as part of update of "DS-dm.cur" informing dependents
                         UP - Curve update ready for "DS-dm.cur"
 # This vector has two curves associated with it.  After it updates, both request updates.
                         UM - Curve "C1" requested update requested for "/home/kst2/kst/tests/dirfile_maker/dm.cur (DS-dm.cur)"
                              Current dependent update list QMap((DirFileSource(0x80ff448) ,  (Kst::Curve(0xb420a298) )  ) )
                         UP - Curve update ready for "DS-dm.cur"
                         UM - Curve "C2" requested update requested for "/home/kst2/kst/tests/dirfile_maker/dm.cur (DS-dm.cur)"
                              Current dependent update list QMap((DirFileSource(0x80ff448) ,  (Kst::Curve(0xb420a298) ,  Kst::Curve(0xb420a998) )  ) )
                 UM - Update finish notification from "V1" for update "DS-dm.cur" update count 1
 # Vector update is finished update count is reduced.
                 UP - Data Source update required by Vector "V2" for update of "DS-dm.cur"
                 UM - Update beginning for "V2" for update "DS-dm.cur" update count 2
                         UP - Vector "V2" has been updated as part of update of "DS-dm.cur" informing dependents
 # Second Vector updating
                         UP - Curve update ready for "DS-dm.cur"
 # One curve associated.  Overlaps V1, no effective change.
                         UM - Curve "C1" requested update requested for "/home/kst2/kst/tests/dirfile_maker/dm.cur (DS-dm.cur)"
                              Current dependent update list QMap((DirFileSource(0x80ff448) ,  (Kst::Curve(0xb420a298) ,  Kst::Curve(0xb420a998) )  ) )
                 UM - Update finish notification from "V2" for update "DS-dm.cur" update count 1
                 UP - Data Source update required by Vector "V3" for update of "DS-dm.cur"
                 UM - Update beginning for "V3" for update "DS-dm.cur" update count 2
                         UP - Vector "V3" has been updated as part of update of "DS-dm.cur" informing dependents
 # Third Vector Updating
                         UP - Curve update ready for "DS-dm.cur"
 # One curve associated.  Overlaps V1, no effective change.
                         UM - Curve "C2" requested update requested for "/home/kst2/kst/tests/dirfile_maker/dm.cur (DS-dm.cur)"
                              Current dependent update list QMap((DirFileSource(0x80ff448) ,  (Kst::Curve(0xb420a298) ,  Kst::Curve(0xb420a998) )  ) )
                 UM - Update finish notification from "V3" for update "DS-dm.cur" update count 1
         UM - Update finish notification from "DS-dm.cur" for update "DS-dm.cur" update count 0
 # All Vectors have now been updated.  The Primitives have all been updated and update count is 0.  Moving on to relations.
         UM - All primitive updates complete updating relations for update of "DS-dm.cur"
              Current dependentUpdate requests QMap((DirFileSource(0x80ff448) ,  (Kst::Curve(0xb420a298) ,  Kst::Curve(0xb420a998) )  ) )
 # Relation Map has been built during Primitive Updates.  Update Manager triggers each.
                 UP - Relation "C1" is processing update of "DS-dm.cur"
                 UM - Update beginning for "C1" for update "DS-dm.cur" update count 1
                 UP - Relation "C1" has been updated as part of update of "DS-dm.cur" informing dependents
 # Updating Curve 1, Plots containing Curve request updates.  Update count is tracked.
                         UP - Curve update required by Plot for update of "DS-dm.cur"
                         UM - Plot update requested for "/home/kst2/kst/tests/dirfile_maker/dm.cur (DS-dm.cur)"
                              Current display update list QMap((DirFileSource(0x80ff448) ,  (0x80d535c) ) )
                         UM - Update finish notification from "C1" for update "DS-dm.cur" update count 0
                 UP - Relation "C2" is processing update of "DS-dm.cur"
 # Finished Updating Curve, Update count reduced.
                 UM - Update beginning for "C2" for update "DS-dm.cur" update count 1
                 UP - Relation "C2" has been updated as part of update of "DS-dm.cur" informing dependents
 # Repeating for Curve 2
                         UP - Curve update required by Plot for update of "DS-dm.cur"
                         UM - Plot update requested for "/home/kst2/kst/tests/dirfile_maker/dm.cur (DS-dm.cur)"
                              Current display update list QMap((DirFileSource(0x80ff448) ,  (0x80d535c, 0x81e0d64) ) )
                         UM - Update finish notification from "C2" for update "DS-dm.cur" update count 0
         UM - All relation updates complete, updating plots for update of "DS-dm.cur"
 # All relations updated, use Map of Plots to trigger update.  No display object is updated until all objects are updated.
              Current display update list QMap((DirFileSource(0x80ff448) ,  (0x80d535c, 0x81e0d64) ) )
                 UP - Updating Plot
                         UP - Updating Plot Projection Rect - X and Y Maximum
 # Plot is updated and if necessary zoom is changed.
                 UP - Updating Plot
                         UP - Updating Plot Projection Rect - X and Y Maximum
         UM - All Plot updates completed for update of  "/home/kst2/kst/tests/dirfile_maker/dm.cur (DS-dm.cur)"
 # Finish of all Plot Updates.
 UM - Update Complete for  "/home/kst2/kst/tests/dirfile_maker/dm.cur (DS-dm.cur)"
 # Finish of Update Cycle
 UM - Delaying for  2000 ms before allowing next update  
 # Delay until next update.